From patchwork Fri Dec 13 19:56:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907821 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D6C2618FC85 for ; Fri, 13 Dec 2024 19:57:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119842; cv=none; b=T0YQ+sFE2LhIp3xqHj2NnclrRt5KrCqIKmkqh7KRl+Kv/q0krE7swSCh2WA08G/E2v20eMr8GFQfKVGCyI9CZ1GjDWMjgBXDDCE0/SJpjQDQmrgSFPbgGIEGVR4A1LRMDlGJY9OHtgqF+61p1vRxfSlmirumcBgxQfeOPZQHjWI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119842; c=relaxed/simple; bh=DkRV07FEYNqjcT3gDeMA06p3a2j0VKh9L00WDYGckW0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=g3vIkw6auzSfmpJuKaL+dMP7+glGNQ7a744laIXeKnHYlC2mCuVhrjFT720GQcZmNTeYfTMVx/xWwQnVcjI1AKTcLkUV0e1cbDvdrmp4Lu09F4R7XXOUCB2XQowALKkgXyGGkRJfQARIK1yGLQ44mH8YEeRx6wU7qCjyYwxmVTo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=C/YeRc7n; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C/YeRc7n" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734119839; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7Vl8Og+1RleSKuFzZ3RLfiwEM4dsj0NWdmQpY187WUI=; b=C/YeRc7nGQ5A4N67PpJ37l48L0aUa81XTjEQ3evgGr6sc3MiExd0WFR254VJHJ4V+b5o8/ kYwnKNButo2/gW4OpaM7vQ4Sp+mlvvDY3G2ra1Jg7Hy7tT5vDYio+6xX2JX9lWQwJYU3eI 5hAjzjZ43oZewYx5PA7l37nOvybGWgU= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-257-LphSi2H_NviWXwwppujiAA-1; Fri, 13 Dec 2024 14:57:16 -0500 X-MC-Unique: LphSi2H_NviWXwwppujiAA-1 X-Mimecast-MFC-AGG-ID: LphSi2H_NviWXwwppujiAA Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2DBE11956046; Fri, 13 Dec 2024 19:57:15 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id D1A441955F40; Fri, 13 Dec 2024 19:57:13 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com Subject: [PATCH 01/18] KVM: x86/mmu: Zap invalid roots with mmu_lock holding for write at uninit Date: Fri, 13 Dec 2024 14:56:54 -0500 Message-ID: <20241213195711.316050-2-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 From: Rick Edgecombe Add a bool parameter to kvm_tdp_mmu_zap_invalidated_roots() to specify zapping invalid roots under mmu_lock held for read or write. Hold mmu_lock for write when kvm_tdp_mmu_zap_invalidated_roots() is called by kvm_mmu_uninit_tdp_mmu(). kvm_mmu_uninit_tdp_mmu() is invoked either before or after executing any atomic operations on SPTEs by vCPU threads. Therefore, it will not impact vCPU threads performance if kvm_tdp_mmu_zap_invalidated_roots() acquires mmu_lock for write to zap invalid roots. This is a preparation for future TDX patch which asserts that "Users of atomic zapping don't operate on mirror roots". Co-developed-by: Yan Zhao Signed-off-by: Yan Zhao Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-2-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 2 +- arch/x86/kvm/mmu/tdp_mmu.c | 16 +++++++++++----- arch/x86/kvm/mmu/tdp_mmu.h | 2 +- 3 files changed, 13 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 22e7ad235123..98b94905e231 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6479,7 +6479,7 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) * lead to use-after-free. */ if (tdp_mmu_enabled) - kvm_tdp_mmu_zap_invalidated_roots(kvm); + kvm_tdp_mmu_zap_invalidated_roots(kvm, true); } void kvm_mmu_init_vm(struct kvm *kvm) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 4508d868f1cd..b0bddcb2f781 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -38,7 +38,7 @@ void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) * ultimately frees all roots. */ kvm_tdp_mmu_invalidate_all_roots(kvm); - kvm_tdp_mmu_zap_invalidated_roots(kvm); + kvm_tdp_mmu_zap_invalidated_roots(kvm, false); WARN_ON(atomic64_read(&kvm->arch.tdp_mmu_pages)); WARN_ON(!list_empty(&kvm->arch.tdp_mmu_roots)); @@ -883,11 +883,14 @@ void kvm_tdp_mmu_zap_all(struct kvm *kvm) * Zap all invalidated roots to ensure all SPTEs are dropped before the "fast * zap" completes. */ -void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm) +void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm, bool shared) { struct kvm_mmu_page *root; - read_lock(&kvm->mmu_lock); + if (shared) + read_lock(&kvm->mmu_lock); + else + write_lock(&kvm->mmu_lock); for_each_tdp_mmu_root_yield_safe(kvm, root) { if (!root->tdp_mmu_scheduled_root_to_zap) @@ -905,7 +908,7 @@ void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm) * that may be zapped, as such entries are associated with the * ASID on both VMX and SVM. */ - tdp_mmu_zap_root(kvm, root, true); + tdp_mmu_zap_root(kvm, root, shared); /* * The referenced needs to be put *after* zapping the root, as @@ -915,7 +918,10 @@ void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm) kvm_tdp_mmu_put_root(kvm, root); } - read_unlock(&kvm->mmu_lock); + if (shared) + read_unlock(&kvm->mmu_lock); + else + write_unlock(&kvm->mmu_lock); } /* diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index f03ca0dd13d9..6d7cdc462f58 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -23,7 +23,7 @@ bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, gfn_t start, gfn_t end, bool flush); bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp); void kvm_tdp_mmu_zap_all(struct kvm *kvm); void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm); -void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm); +void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm, bool shared); int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); From patchwork Fri Dec 13 19:56:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907825 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 77CD41E8836 for ; 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Fri, 13 Dec 2024 14:57:19 -0500 X-MC-Unique: R03LvABiNliXyRJZcsabMQ-1 X-Mimecast-MFC-AGG-ID: R03LvABiNliXyRJZcsabMQ Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 557A519560B1; Fri, 13 Dec 2024 19:57:16 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 61130195605A; Fri, 13 Dec 2024 19:57:15 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com Subject: [PATCH 02/18] KVM: Add member to struct kvm_gfn_range for target alias Date: Fri, 13 Dec 2024 14:56:55 -0500 Message-ID: <20241213195711.316050-3-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 From: Isaku Yamahata Add new members to strut kvm_gfn_range to indicate which mapping (private-vs-shared) to operate on: enum kvm_gfn_range_filter attr_filter. Update the core zapping operations to set them appropriately. TDX utilizes two GPA aliases for the same memslots, one for memory that is for private memory and one that is for shared. For private memory, KVM cannot always perform the same operations it does on memory for default VMs, such as zapping pages and having them be faulted back in, as this requires guest coordination. However, some operations such as guest driven conversion of memory between private and shared should zap private memory. Internally to the MMU, private and shared mappings are tracked on separate roots. Mapping and zapping operations will operate on the respective GFN alias for each root (private or shared). So zapping operations will by default zap both aliases. Add fields in struct kvm_gfn_range to allow callers to specify which aliases so they can only target the aliases appropriate for their specific operation. There was feedback that target aliases should be specified such that the default value (0) is to operate on both aliases. Several options were considered. Several variations of having separate bools defined such that the default behavior was to process both aliases. They either allowed nonsensical configurations, or were confusing for the caller. A simple enum was also explored and was close, but was hard to process in the caller. Instead, use an enum with the default value (0) reserved as a disallowed value. Catch ranges that didn't have the target aliases specified by looking for that specific value. Set target alias with enum appropriately for these MMU operations: - For KVM's mmu notifier callbacks, zap shared pages only because private pages won't have a userspace mapping - For setting memory attributes, kvm_arch_pre_set_memory_attributes() chooses the aliases based on the attribute. - For guest_memfd invalidations, zap private only. Link: https://lore.kernel.org/kvm/ZivIF9vjKcuGie3s@google.com/ Signed-off-by: Isaku Yamahata Co-developed-by: Rick Edgecombe Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-3-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 6 ++++++ include/linux/kvm_host.h | 6 ++++++ virt/kvm/guest_memfd.c | 2 ++ virt/kvm/kvm_main.c | 14 ++++++++++++++ 4 files changed, 28 insertions(+) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 98b94905e231..e87f22e8dd44 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -7464,6 +7464,12 @@ bool kvm_arch_pre_set_memory_attributes(struct kvm *kvm, if (WARN_ON_ONCE(!kvm_arch_has_private_mem(kvm))) return false; + /* Unmap the old attribute page. */ + if (range->arg.attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE) + range->attr_filter = KVM_FILTER_SHARED; + else + range->attr_filter = KVM_FILTER_PRIVATE; + return kvm_unmap_gfn_range(kvm, range); } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 401439bb21e3..9db304d14c46 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -255,11 +255,17 @@ union kvm_mmu_notifier_arg { unsigned long attributes; }; +enum kvm_gfn_range_filter { + KVM_FILTER_SHARED = BIT(0), + KVM_FILTER_PRIVATE = BIT(1), +}; + struct kvm_gfn_range { struct kvm_memory_slot *slot; gfn_t start; gfn_t end; union kvm_mmu_notifier_arg arg; + enum kvm_gfn_range_filter attr_filter; bool may_block; }; bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range); diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 47a9f68f7b24..651c2f08df62 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -118,6 +118,8 @@ static void kvm_gmem_invalidate_begin(struct kvm_gmem *gmem, pgoff_t start, .end = slot->base_gfn + min(pgoff + slot->npages, end) - pgoff, .slot = slot, .may_block = true, + /* guest memfd is relevant to only private mappings. */ + .attr_filter = KVM_FILTER_PRIVATE, }; if (!found_memslot) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index de2c11dae231..164cd4f7f8ba 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -594,6 +594,11 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, */ gfn_range.arg = range->arg; gfn_range.may_block = range->may_block; + /* + * HVA-based notifications aren't relevant to private + * mappings as they don't have a userspace mapping. + */ + gfn_range.attr_filter = KVM_FILTER_SHARED; /* * {gfn(page) | page intersects with [hva_start, hva_end)} = @@ -2408,6 +2413,14 @@ static __always_inline void kvm_handle_gfn_range(struct kvm *kvm, gfn_range.arg = range->arg; gfn_range.may_block = range->may_block; + /* + * If/when KVM supports more attributes beyond private .vs shared, this + * _could_ set KVM_FILTER_{SHARED,PRIVATE} appropriately if the entire target + * range already has the desired private vs. shared state (it's unclear + * if that is a net win). For now, KVM reaches this point if and only + * if the private flag is being toggled, i.e. all mappings are in play. + */ + for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { slots = __kvm_memslots(kvm, i); @@ -2464,6 +2477,7 @@ static int kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end, struct kvm_mmu_notifier_range pre_set_range = { .start = start, .end = end, + .arg.attributes = attributes, .handler = kvm_pre_set_memory_attributes, .on_lock = kvm_mmu_invalidate_begin, .flush_on_ret = true, From patchwork Fri Dec 13 19:56:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907824 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 558131EBA07 for ; Fri, 13 Dec 2024 19:57:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119847; cv=none; b=C5/byJLBuYxbVDh+kxOEz3I2zU01FPRiN0KALG5aC4DPjRd8C9yd7snJglCKpoMJ+w5kBL1vd5ChKBvIwf/KY8CJtelpBoS5fBAAvFS0lID8JfYFHoQJ94lEWOcDmrHmI54EjV20moT3X0K0bkeygft3QQFVQqUHh9kY+Dc8paA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119847; c=relaxed/simple; bh=sthHUtFKrqUaPxQfCF60mgyDHtH6m55/15Jq0vpOz5c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=W7s7hp/UyzNi1vZ5/x3RhkR49TgBtZ6SCaDens7ImdZ+49h8Q99cyGpjDpMHjaIyeIXVgyU+AnqJxe8bUJMIgL+zFeH6CeN9AtBudRpXcf31ohvD/MA6Aj3R40LTlSUOQDY/VTSEqoiFLzJQ4seBoLvk8gFVDBpGNLVYwRQ5xSQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=TDOmyd8C; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TDOmyd8C" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734119844; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qcwioA+8IUPWsl77mjGc+fBvaRQn2foraJmcVc4D09c=; b=TDOmyd8CTlRq3smkGLbx+zn/cS9PPwckKVGbyUFsPpXv2XRCvgAjeiLdQ/ecwzg3oPUyVt 2BFM1aeiNDUwOrLvFASjKLxjuNOOI2fsnf3twC/2OIYDJV9WzVYdX4mzUU94LlLBW9OxEu dsny8Kqike4kKsvVJmlDbtJFFp5dnu4= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-401-as6MmIRqNQmgjgOoiinsUQ-1; Fri, 13 Dec 2024 14:57:18 -0500 X-MC-Unique: as6MmIRqNQmgjgOoiinsUQ-1 X-Mimecast-MFC-AGG-ID: as6MmIRqNQmgjgOoiinsUQ Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 86BB6195609E; Fri, 13 Dec 2024 19:57:17 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 89D901955F3C; Fri, 13 Dec 2024 19:57:16 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com Subject: [PATCH 03/18] KVM: x86: Add a VM type define for TDX Date: Fri, 13 Dec 2024 14:56:56 -0500 Message-ID: <20241213195711.316050-4-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 From: Rick Edgecombe Add a VM type define for TDX. Future changes will need to lay the ground work for TDX support by making some behavior conditional on the VM being a TDX guest. Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-4-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/uapi/asm/kvm.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index 88585c1de416..9e75da97bce0 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -925,5 +925,6 @@ struct kvm_hyperv_eventfd { #define KVM_X86_SEV_VM 2 #define KVM_X86_SEV_ES_VM 3 #define KVM_X86_SNP_VM 4 +#define KVM_X86_TDX_VM 5 #endif /* _ASM_X86_KVM_H */ From patchwork Fri Dec 13 19:56:57 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907826 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1C0001E8839 for ; Fri, 13 Dec 2024 19:57:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119847; cv=none; b=ph8i3j9aXV0trhOmpFcCklrz0tENjO4EXA9kwqknLuZXdXncJL48kQ5ky1MvpD1914xKpiaScJCQXne0nEx4vT12XuUuLTaBohq//gSgOjrgDE95rhIPtc0rpFHfgCNUMAMgO8INUWCuNm25j6NYZQjma93YJoT1v9g1tkVWrCM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119847; c=relaxed/simple; bh=/IwTpj+UAyxrOOLurzt+l1sLLKRzY1gIFHEoxNQPQPQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=hxZMMQwsrgavDn0k301e7JxZH99fwr8urKxV6oMVEuyEwZ3XmtGKgksAnFyzU5rqAIoaEY4Gugkee66G5sK4zUkhydva0nvohZgUNz/vPUDz5ehGcWlQxL89NMA84FWHej/SgHuqqkdiBs9nLyzqr/lvF2/Tl9CMYB82FNGFVqA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=MfWwHX/X; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MfWwHX/X" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734119844; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hje4JKHr4ghgBal4NU6uwLrFHCTJ6qK8Xyxe/U8+Vs4=; b=MfWwHX/X28t0ydS8PvgZbDJU5lxPiS7S/D6mWl3ke7IuLYXNTF1vzmYlXzJDK34xScw2wb xhKn56OT3Z4T9Q5HD73HBjIyk0D6AQpdI5pf498E/wbmXwTblilB7Q+kbo2soVdffdch+u 5Tstw88K7BxY7/MLg6hlNjqhWoOYFCo= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-488-OFS6tqJXO_ysJLokL05ogA-1; Fri, 13 Dec 2024 14:57:20 -0500 X-MC-Unique: OFS6tqJXO_ysJLokL05ogA-1 X-Mimecast-MFC-AGG-ID: OFS6tqJXO_ysJLokL05ogA Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B3A3519560B3; Fri, 13 Dec 2024 19:57:18 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B848A195605A; Fri, 13 Dec 2024 19:57:17 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com Subject: [PATCH 04/18] KVM: x86/mmu: Add an external pointer to struct kvm_mmu_page Date: Fri, 13 Dec 2024 14:56:57 -0500 Message-ID: <20241213195711.316050-5-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 From: Isaku Yamahata Add a external pointer to struct kvm_mmu_page for TDX's private page table and add helper functions to allocate/initialize/free a private page table page. TDX will only be supported with the TDP MMU. Because KVM TDP MMU doesn't use unsync_children and write_flooding_count, pack them to have room for a pointer and use a union to avoid memory overhead. For private GPA, CPU refers to a private page table whose contents are encrypted. The dedicated APIs to operate on it (e.g. updating/reading its PTE entry) are used, and their cost is expensive. When KVM resolves the KVM page fault, it walks the page tables. To reuse the existing KVM MMU code and mitigate the heavy cost of directly walking the private page table allocate two sets of page tables for the private half of the GPA space. For the page tables that KVM will walk, allocate them like normal and refer to them as mirror page tables. Additionally allocate one more page for the page tables the CPU will walk, and call them external page tables. Resolve the KVM page fault with the existing code, and do additional operations necessary for modifying the external page table in future patches. The relationship of the types of page tables in this scheme is depicted below: KVM page fault | | | V | -------------+---------- | | | | V V | shared GPA private GPA | | | | V V | shared PT root mirror PT root | private PT root | | | | V V | V shared PT mirror PT --propagate--> external PT | | | | | \-----------------+------\ | | | | | V | V V shared guest page | private guest page | non-encrypted memory | encrypted memory | PT - Page table Shared PT - Visible to KVM, and the CPU uses it for shared mappings. External PT - The CPU uses it, but it is invisible to KVM. TDX module updates this table to map private guest pages. Mirror PT - It is visible to KVM, but the CPU doesn't use it. KVM uses it to propagate PT change to the actual private PT. Add a helper kvm_has_mirrored_tdp() to trigger this behavior and wire it to the TDX vm type. Co-developed-by: Yan Zhao Signed-off-by: Yan Zhao Signed-off-by: Isaku Yamahata Signed-off-by: Rick Edgecombe Reviewed-by: Binbin Wu Message-ID: <20240718211230.1492011-5-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 5 +++++ arch/x86/kvm/mmu.h | 5 +++++ arch/x86/kvm/mmu/mmu.c | 7 +++++++ arch/x86/kvm/mmu/mmu_internal.h | 31 +++++++++++++++++++++++++++---- arch/x86/kvm/mmu/tdp_mmu.c | 1 + 5 files changed, 45 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index c1251b371421..5f020b097922 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -813,6 +813,11 @@ struct kvm_vcpu_arch { struct kvm_mmu_memory_cache mmu_shadow_page_cache; struct kvm_mmu_memory_cache mmu_shadowed_info_cache; struct kvm_mmu_memory_cache mmu_page_header_cache; + /* + * This cache is to allocate external page table. E.g. private EPT used + * by the TDX module. + */ + struct kvm_mmu_memory_cache mmu_external_spt_cache; /* * QEMU userspace and the guest each have their own FPU state. diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index e9322358678b..538eb3156f09 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -287,4 +287,9 @@ static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu, return gpa; return translate_nested_gpa(vcpu, gpa, access, exception); } + +static inline bool kvm_has_mirrored_tdp(const struct kvm *kvm) +{ + return kvm->arch.vm_type == KVM_X86_TDX_VM; +} #endif diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index e87f22e8dd44..b2a6cddde643 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -599,6 +599,12 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect) 1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM); if (r) return r; + if (kvm_has_mirrored_tdp(vcpu->kvm)) { + r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_external_spt_cache, + PT64_ROOT_MAX_LEVEL); + if (r) + return r; + } r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache, PT64_ROOT_MAX_LEVEL); if (r) @@ -618,6 +624,7 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu) kvm_mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache); kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache); kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadowed_info_cache); + kvm_mmu_free_memory_cache(&vcpu->arch.mmu_external_spt_cache); kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache); } diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index b00abbe3f6cf..d9425064ecc5 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -101,7 +101,22 @@ struct kvm_mmu_page { int root_count; refcount_t tdp_mmu_root_count; }; - unsigned int unsync_children; + union { + /* These two members aren't used for TDP MMU */ + struct { + unsigned int unsync_children; + /* + * Number of writes since the last time traversal + * visited this page. + */ + atomic_t write_flooding_count; + }; + /* + * Page table page of external PT. + * Passed to TDX module, not accessed by KVM. + */ + void *external_spt; + }; union { struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */ tdp_ptep_t ptep; @@ -124,9 +139,6 @@ struct kvm_mmu_page { int clear_spte_count; #endif - /* Number of writes since the last time traversal visited this page. */ - atomic_t write_flooding_count; - #ifdef CONFIG_X86_64 /* Used for freeing the page asynchronously if it is a TDP MMU page. */ struct rcu_head rcu_head; @@ -145,6 +157,17 @@ static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp) return kvm_mmu_role_as_id(sp->role); } +static inline void kvm_mmu_alloc_external_spt(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) +{ + /* + * external_spt is allocated for TDX module to hold private EPT mappings, + * TDX module will initialize the page by itself. + * Therefore, KVM does not need to initialize or access external_spt. + * KVM only interacts with sp->spt for private EPT operations. + */ + sp->external_spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_external_spt_cache); 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The TDX module maintains the private half of the EPT mapped in the TD in its protected memory. KVM keeps a copy of the private GPAs in a mirrored EPT tree within host memory. This "is_mirror" attribute enables vCPUs to find and get the root page of mirrored EPT from the MMU root list for a guest TD. This also allows KVM MMU code to detect changes in mirrored EPT according to the "is_mirror" mmu page role and propagate the changes to the private EPT managed by TDX module. Signed-off-by: Isaku Yamahata Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-6-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 3 ++- arch/x86/kvm/mmu/mmu_internal.h | 5 +++++ arch/x86/kvm/mmu/spte.h | 5 +++++ 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 5f020b097922..cae88f023caf 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -349,7 +349,8 @@ union kvm_mmu_page_role { unsigned ad_disabled:1; unsigned guest_mode:1; unsigned passthrough:1; - unsigned :5; + unsigned is_mirror:1; + unsigned :4; /* * This is left at the top of the word so that diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index d9425064ecc5..ff00341f26a2 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -157,6 +157,11 @@ static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp) return kvm_mmu_role_as_id(sp->role); 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This allows for the caller, mmu_alloc_direct_roots(), to call kvm_tdp_mmu_alloc_root() and also return 0 in one line: return kvm_tdp_mmu_alloc_root(vcpu); So it is useful even though the return value of kvm_tdp_mmu_alloc_root() is always the same. However, in future changes, kvm_tdp_mmu_alloc_root() will be called twice in mmu_alloc_direct_roots(). This will force the first call to either awkwardly handle the return value that will always be zero or ignore it. So change kvm_tdp_mmu_alloc_root() to return void. Do it in a separate change so the future change will be cleaner. Signed-off-by: Rick Edgecombe Reviewed-by: Paolo Bonzini Message-ID: <20240718211230.1492011-7-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 6 ++++-- arch/x86/kvm/mmu/tdp_mmu.c | 3 +-- arch/x86/kvm/mmu/tdp_mmu.h | 2 +- 3 files changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index b2a6cddde643..9b6c28b30298 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3675,8 +3675,10 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) unsigned i; int r; - if (tdp_mmu_enabled) - return kvm_tdp_mmu_alloc_root(vcpu); + if (tdp_mmu_enabled) { + kvm_tdp_mmu_alloc_root(vcpu); + return 0; + } write_lock(&vcpu->kvm->mmu_lock); r = make_mmu_pages_available(vcpu); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 633c07c63fa6..0d179653f959 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -224,7 +224,7 @@ static void tdp_mmu_init_child_sp(struct kvm_mmu_page *child_sp, tdp_mmu_init_sp(child_sp, iter->sptep, iter->gfn, role); } -int kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu) +void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu) { struct kvm_mmu *mmu = vcpu->arch.mmu; union kvm_mmu_page_role role = mmu->root_role; @@ -285,7 +285,6 @@ int kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu) */ mmu->root.hpa = __pa(root->spt); mmu->root.pgd = 0; - return 0; } static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index 6d7cdc462f58..51884fc6a512 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -10,7 +10,7 @@ void kvm_mmu_init_tdp_mmu(struct kvm *kvm); void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm); -int kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu); +void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu); __must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root) { From patchwork Fri Dec 13 19:57:00 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907830 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A5F621F1936 for ; 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Future changes will want to change how the iterator behaves based on a member of struct kvm. Change the signature and callers of the iterator loop helpers in a separate patch to make the future one easier to review. Signed-off-by: Isaku Yamahata Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-8-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/tdp_iter.h | 6 +++--- arch/x86/kvm/mmu/tdp_mmu.c | 38 ++++++++++++++++++------------------- 2 files changed, 22 insertions(+), 22 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h index 2880fd392e0c..d8f2884e3c66 100644 --- a/arch/x86/kvm/mmu/tdp_iter.h +++ b/arch/x86/kvm/mmu/tdp_iter.h @@ -122,13 +122,13 @@ struct tdp_iter { * Iterates over every SPTE mapping the GFN range [start, end) in a * preorder traversal. */ -#define for_each_tdp_pte_min_level(iter, root, min_level, start, end) \ +#define for_each_tdp_pte_min_level(iter, kvm, root, min_level, start, end) \ for (tdp_iter_start(&iter, root, min_level, start); \ iter.valid && iter.gfn < end; \ tdp_iter_next(&iter)) -#define for_each_tdp_pte(iter, root, start, end) \ - for_each_tdp_pte_min_level(iter, root, PG_LEVEL_4K, start, end) +#define for_each_tdp_pte(iter, kvm, root, start, end) \ + for_each_tdp_pte_min_level(iter, kvm, root, PG_LEVEL_4K, start, end) tdp_ptep_t spte_to_child_pt(u64 pte, int level); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 0d179653f959..6fb49f595d68 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -625,18 +625,18 @@ static inline void tdp_mmu_iter_set_spte(struct kvm *kvm, struct tdp_iter *iter, iter->gfn, iter->level); } -#define tdp_root_for_each_pte(_iter, _root, _start, _end) \ - for_each_tdp_pte(_iter, _root, _start, _end) +#define tdp_root_for_each_pte(_iter, _kvm, _root, _start, _end) \ + for_each_tdp_pte(_iter, _kvm, _root, _start, _end) -#define tdp_root_for_each_leaf_pte(_iter, _root, _start, _end) \ - tdp_root_for_each_pte(_iter, _root, _start, _end) \ +#define tdp_root_for_each_leaf_pte(_iter, _kvm, _root, _start, _end) \ + tdp_root_for_each_pte(_iter, _kvm, _root, _start, _end) \ if (!is_shadow_present_pte(_iter.old_spte) || \ !is_last_spte(_iter.old_spte, _iter.level)) \ continue; \ else -#define tdp_mmu_for_each_pte(_iter, _mmu, _start, _end) \ - for_each_tdp_pte(_iter, root_to_sp(_mmu->root.hpa), _start, _end) +#define tdp_mmu_for_each_pte(_iter, _kvm, _mmu, _start, _end) \ + for_each_tdp_pte(_iter, _kvm, root_to_sp(_mmu->root.hpa), _start, _end) static inline bool __must_check tdp_mmu_iter_need_resched(struct kvm *kvm, struct tdp_iter *iter) @@ -708,7 +708,7 @@ static void __tdp_mmu_zap_root(struct kvm *kvm, struct kvm_mmu_page *root, gfn_t end = tdp_mmu_max_gfn_exclusive(); gfn_t start = 0; - for_each_tdp_pte_min_level(iter, root, zap_level, start, end) { + for_each_tdp_pte_min_level(iter, kvm, root, zap_level, start, end) { retry: if (tdp_mmu_iter_cond_resched(kvm, &iter, false, shared)) continue; @@ -812,7 +812,7 @@ static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root, rcu_read_lock(); - for_each_tdp_pte_min_level(iter, root, PG_LEVEL_4K, start, end) { + for_each_tdp_pte_min_level(iter, kvm, root, PG_LEVEL_4K, start, end) { if (can_yield && tdp_mmu_iter_cond_resched(kvm, &iter, flush, false)) { flush = false; @@ -1081,7 +1081,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) rcu_read_lock(); - tdp_mmu_for_each_pte(iter, mmu, fault->gfn, fault->gfn + 1) { + tdp_mmu_for_each_pte(iter, kvm, mmu, fault->gfn, fault->gfn + 1) { int r; if (fault->nx_huge_page_workaround_enabled) @@ -1207,7 +1207,7 @@ static bool __kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, for_each_valid_tdp_mmu_root(kvm, root, range->slot->as_id) { guard(rcu)(); - tdp_root_for_each_leaf_pte(iter, root, range->start, range->end) { + tdp_root_for_each_leaf_pte(iter, kvm, root, range->start, range->end) { if (!is_accessed_spte(iter.old_spte)) continue; @@ -1248,7 +1248,7 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL); - for_each_tdp_pte_min_level(iter, root, min_level, start, end) { + for_each_tdp_pte_min_level(iter, kvm, root, min_level, start, end) { retry: if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) continue; @@ -1367,7 +1367,7 @@ static int tdp_mmu_split_huge_pages_root(struct kvm *kvm, * level above the target level (e.g. splitting a 1GB to 512 2MB pages, * and then splitting each of those to 512 4KB pages). */ - for_each_tdp_pte_min_level(iter, root, target_level + 1, start, end) { + for_each_tdp_pte_min_level(iter, kvm, root, target_level + 1, start, end) { retry: if (tdp_mmu_iter_cond_resched(kvm, &iter, false, shared)) continue; @@ -1465,7 +1465,7 @@ static void clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, rcu_read_lock(); - tdp_root_for_each_pte(iter, root, start, end) { + tdp_root_for_each_pte(iter, kvm, root, start, end) { retry: if (!is_shadow_present_pte(iter.old_spte) || !is_last_spte(iter.old_spte, iter.level)) @@ -1513,7 +1513,7 @@ static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root, rcu_read_lock(); - tdp_root_for_each_leaf_pte(iter, root, gfn + __ffs(mask), + tdp_root_for_each_leaf_pte(iter, kvm, root, gfn + __ffs(mask), gfn + BITS_PER_LONG) { if (!mask) break; @@ -1567,7 +1567,7 @@ static int tdp_mmu_make_huge_spte(struct kvm *kvm, gfn_t end = start + KVM_PAGES_PER_HPAGE(parent->level); struct tdp_iter iter; - tdp_root_for_each_leaf_pte(iter, root, start, end) { + tdp_root_for_each_leaf_pte(iter, kvm, root, start, end) { /* * Use the parent iterator when checking for forward progress so * that KVM doesn't get stuck continuously trying to yield (i.e. @@ -1601,7 +1601,7 @@ static void recover_huge_pages_range(struct kvm *kvm, rcu_read_lock(); - for_each_tdp_pte_min_level(iter, root, PG_LEVEL_2M, start, end) { + for_each_tdp_pte_min_level(iter, kvm, root, PG_LEVEL_2M, start, end) { retry: if (tdp_mmu_iter_cond_resched(kvm, &iter, flush, true)) { flush = false; @@ -1682,7 +1682,7 @@ static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root, rcu_read_lock(); - for_each_tdp_pte_min_level(iter, root, min_level, gfn, gfn + 1) { + for_each_tdp_pte_min_level(iter, kvm, root, min_level, gfn, gfn + 1) { if (!is_shadow_present_pte(iter.old_spte) || !is_last_spte(iter.old_spte, iter.level)) continue; @@ -1737,7 +1737,7 @@ int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, *root_level = vcpu->arch.mmu->root_role.level; - tdp_mmu_for_each_pte(iter, mmu, gfn, gfn + 1) { + tdp_mmu_for_each_pte(iter, vcpu->kvm, mmu, gfn, gfn + 1) { leaf = iter.level; sptes[leaf] = iter.old_spte; } @@ -1763,7 +1763,7 @@ u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_mmu *mmu = vcpu->arch.mmu; tdp_ptep_t sptep = NULL; - tdp_mmu_for_each_pte(iter, mmu, gfn, gfn + 1) { + tdp_mmu_for_each_pte(iter, vcpu->kvm, mmu, gfn, gfn + 1) { *spte = iter.old_spte; sptep = iter.sptep; } From patchwork Fri Dec 13 19:57:01 2024 Content-Type: text/plain; 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Fri, 13 Dec 2024 19:57:23 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 60EF5195605A; Fri, 13 Dec 2024 19:57:22 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com Subject: [PATCH 08/18] KVM: x86/mmu: Support GFN direct bits Date: Fri, 13 Dec 2024 14:57:01 -0500 Message-ID: <20241213195711.316050-9-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 From: Isaku Yamahata Teach the MMU to map guest GFNs at a massaged position on the TDP, to aid in implementing TDX shared memory. Like other Coco technologies, TDX has the concept of private and shared memory. For TDX the private and shared mappings are managed on separate EPT roots. The private half is managed indirectly through calls into a protected runtime environment called the TDX module, where the shared half is managed within KVM in normal page tables. For TDX, the shared half will be mapped in the higher alias, with a "shared bit" set in the GPA. However, KVM will still manage it with the same memslots as the private half. This means memslot looks ups and zapping operations will be provided with a GFN without the shared bit set. So KVM will either need to apply or strip the shared bit before mapping or zapping the shared EPT. Having GFNs sometimes have the shared bit and sometimes not would make the code confusing. So instead arrange the code such that GFNs never have shared bit set. Create a concept of "direct bits", that is stripped from the fault address when setting fault->gfn, and applied within the TDP MMU iterator. Calling code will behave as if it is operating on the PTE mapping the GFN (without shared bits) but within the iterator, the actual mappings will be shifted using bits specific for the root. SPs will have the GFN set without the shared bit. In the end the TDP MMU will behave like it is mapping things at the GFN without the shared bit but with a strange page table format where everything is offset by the shared bit. Since TDX only needs to shift the mapping like this for the shared bit, which is mapped as the normal TDP root, add a "gfn_direct_bits" field to the kvm_arch structure for each VM with a default value of 0. It will have the bit set at the position of the GPA shared bit in GFN through TD specific initialization code. Keep TDX specific concepts out of the MMU code by not naming it "shared". Ranged TLB flushes (i.e. flush_remote_tlbs_range()) target specific GFN ranges. In convention established above, these would need to target the shifted GFN range. It won't matter functionally, since the actual implementation will always result in a full flush for the only planned user (TDX). For correctness reasons, future changes can provide a TDX x86_ops.flush_remote_tlbs_range implementation to return -EOPNOTSUPP and force the full flush for TDs. This leaves one problem. Some operations use a concept of max GFN (i.e. kvm_mmu_max_gfn()), to iterate over the whole TDP range. When applying the direct mask to the start of the range, the iterator would end up skipping iterating over the range not covered by the direct mask bit. For safety, make sure the __tdp_mmu_zap_root() operation iterates over the full GFN range supported by the underlying TDP format. Add a new iterator helper, for_each_tdp_pte_min_level_all(), that iterates the entire TDP GFN range, regardless of root. Signed-off-by: Isaku Yamahata Co-developed-by: Yan Zhao Signed-off-by: Yan Zhao Co-developed-by: Rick Edgecombe Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-9-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/mmu.h | 5 +++++ arch/x86/kvm/mmu/mmu_internal.h | 28 ++++++++++++++++++++++++++-- arch/x86/kvm/mmu/tdp_iter.c | 10 ++++++---- arch/x86/kvm/mmu/tdp_iter.h | 15 +++++++++++---- arch/x86/kvm/mmu/tdp_mmu.c | 5 +---- 6 files changed, 51 insertions(+), 14 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index cae88f023caf..95f2b0890a58 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1542,6 +1542,8 @@ struct kvm_arch { */ #define SPLIT_DESC_CACHE_MIN_NR_OBJECTS (SPTE_ENT_PER_PAGE + 1) struct kvm_mmu_memory_cache split_desc_cache; + + gfn_t gfn_direct_bits; }; struct kvm_vm_stat { diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 538eb3156f09..091002975374 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -292,4 +292,9 @@ static inline bool kvm_has_mirrored_tdp(const struct kvm *kvm) { return kvm->arch.vm_type == KVM_X86_TDX_VM; } + +static inline gfn_t kvm_gfn_direct_bits(const struct kvm *kvm) +{ + return kvm->arch.gfn_direct_bits; +} #endif diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index ff00341f26a2..957636660149 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -6,6 +6,8 @@ #include #include +#include "mmu.h" + #ifdef CONFIG_KVM_PROVE_MMU #define KVM_MMU_WARN_ON(x) WARN_ON_ONCE(x) #else @@ -173,6 +175,18 @@ static inline void kvm_mmu_alloc_external_spt(struct kvm_vcpu *vcpu, struct kvm_ sp->external_spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_external_spt_cache); } +static inline gfn_t kvm_gfn_root_bits(const struct kvm *kvm, const struct kvm_mmu_page *root) +{ + /* + * Since mirror SPs are used only for TDX, which maps private memory + * at its "natural" GFN, no mask needs to be applied to them - and, dually, + * we expect that the bits is only used for the shared PT. + */ + if (is_mirror_sp(root)) + return 0; + return kvm_gfn_direct_bits(kvm); +} + static inline bool kvm_mmu_page_ad_need_write_protect(struct kvm_mmu_page *sp) { /* @@ -257,7 +271,12 @@ struct kvm_page_fault { */ u8 goal_level; - /* Shifted addr, or result of guest page table walk if addr is a gva. */ + /* + * Shifted addr, or result of guest page table walk if addr is a gva. In + * the case of VM where memslot's can be mapped at multiple GPA aliases + * (i.e. TDX), the gfn field does not contain the bit that selects between + * the aliases (i.e. the shared bit for TDX). + */ gfn_t gfn; /* The memslot containing gfn. May be NULL. */ @@ -345,7 +364,12 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, int r; if (vcpu->arch.mmu->root_role.direct) { - fault.gfn = fault.addr >> PAGE_SHIFT; + /* + * Things like memslots don't understand the concept of a shared + * bit. Strip it so that the GFN can be used like normal, and the + * fault.addr can be used when the shared bit is needed. + */ + fault.gfn = gpa_to_gfn(fault.addr) & ~kvm_gfn_direct_bits(vcpu->kvm); fault.slot = kvm_vcpu_gfn_to_memslot(vcpu, fault.gfn); } diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c index 04c247bfe318..9e17bfa80901 100644 --- a/arch/x86/kvm/mmu/tdp_iter.c +++ b/arch/x86/kvm/mmu/tdp_iter.c @@ -12,7 +12,7 @@ static void tdp_iter_refresh_sptep(struct tdp_iter *iter) { iter->sptep = iter->pt_path[iter->level - 1] + - SPTE_INDEX(iter->gfn << PAGE_SHIFT, iter->level); + SPTE_INDEX((iter->gfn | iter->gfn_bits) << PAGE_SHIFT, iter->level); iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep); } @@ -37,15 +37,17 @@ void tdp_iter_restart(struct tdp_iter *iter) * rooted at root_pt, starting with the walk to translate next_last_level_gfn. */ void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root, - int min_level, gfn_t next_last_level_gfn) + int min_level, gfn_t next_last_level_gfn, gfn_t gfn_bits) { if (WARN_ON_ONCE(!root || (root->role.level < 1) || - (root->role.level > PT64_ROOT_MAX_LEVEL))) { + (root->role.level > PT64_ROOT_MAX_LEVEL) || + (gfn_bits && next_last_level_gfn >= gfn_bits))) { iter->valid = false; return; } iter->next_last_level_gfn = next_last_level_gfn; + iter->gfn_bits = gfn_bits; iter->root_level = root->role.level; iter->min_level = min_level; iter->pt_path[iter->root_level - 1] = (tdp_ptep_t)root->spt; @@ -113,7 +115,7 @@ static bool try_step_side(struct tdp_iter *iter) * Check if the iterator is already at the end of the current page * table. */ - if (SPTE_INDEX(iter->gfn << PAGE_SHIFT, iter->level) == + if (SPTE_INDEX((iter->gfn | iter->gfn_bits) << PAGE_SHIFT, iter->level) == (SPTE_ENT_PER_PAGE - 1)) return false; diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h index d8f2884e3c66..047b78333653 100644 --- a/arch/x86/kvm/mmu/tdp_iter.h +++ b/arch/x86/kvm/mmu/tdp_iter.h @@ -93,8 +93,10 @@ struct tdp_iter { tdp_ptep_t pt_path[PT64_ROOT_MAX_LEVEL]; /* A pointer to the current SPTE */ tdp_ptep_t sptep; - /* The lowest GFN mapped by the current SPTE */ + /* The lowest GFN (mask bits excluded) mapped by the current SPTE */ gfn_t gfn; + /* Mask applied to convert the GFN to the mapping GPA */ + gfn_t gfn_bits; /* The level of the root page given to the iterator */ int root_level; /* The lowest level the iterator should traverse to */ @@ -123,17 +125,22 @@ struct tdp_iter { * preorder traversal. */ #define for_each_tdp_pte_min_level(iter, kvm, root, min_level, start, end) \ - for (tdp_iter_start(&iter, root, min_level, start); \ - iter.valid && iter.gfn < end; \ + for (tdp_iter_start(&iter, root, min_level, start, kvm_gfn_root_bits(kvm, root)); \ + iter.valid && iter.gfn < end; \ tdp_iter_next(&iter)) +#define for_each_tdp_pte_min_level_all(iter, root, min_level) \ + for (tdp_iter_start(&iter, root, min_level, 0, 0); \ + iter.valid && iter.gfn < tdp_mmu_max_gfn_exclusive(); \ + tdp_iter_next(&iter)) + #define for_each_tdp_pte(iter, kvm, root, start, end) \ for_each_tdp_pte_min_level(iter, kvm, root, PG_LEVEL_4K, start, end) tdp_ptep_t spte_to_child_pt(u64 pte, int level); void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root, - int min_level, gfn_t next_last_level_gfn); + int min_level, gfn_t next_last_level_gfn, gfn_t gfn_bits); 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It checks only_invalid now. TDX KVM operates on a shared page table only (Shared-EPT), a mirrored page table only (Secure-EPT), or both based on the operation. KVM MMU notifier operations only on shared page table. KVM guest_memfd invalidation operations only on mirrored page table, and so on. Introduce a centralized matching function instead of open coding matching logic in the iterator. The next step is to extend the function to check whether the page is shared or private Link: https://lore.kernel.org/kvm/ZivazWQw1oCU8VBC@google.com/ Signed-off-by: Isaku Yamahata Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-10-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/tdp_mmu.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index c77cbf2577c3..fbf835469390 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -92,6 +92,14 @@ void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root) call_rcu(&root->rcu_head, tdp_mmu_free_sp_rcu_callback); } +static bool tdp_mmu_root_match(struct kvm_mmu_page *root, bool only_valid) +{ + if (only_valid && root->role.invalid) + return false; + + return true; +} + /* * Returns the next root after @prev_root (or the first root if @prev_root is * NULL). 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Fri, 13 Dec 2024 14:57:28 -0500 X-MC-Unique: 9TCrqlqaMR-9NVyxlPsDzg-1 X-Mimecast-MFC-AGG-ID: 9TCrqlqaMR-9NVyxlPsDzg Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 732C919560B4; Fri, 13 Dec 2024 19:57:26 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 62F791956089; Fri, 13 Dec 2024 19:57:25 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com, Sean Christopherson Subject: [PATCH 10/18] KVM: x86/tdp_mmu: Introduce KVM MMU root types to specify page table type Date: Fri, 13 Dec 2024 14:57:03 -0500 Message-ID: <20241213195711.316050-11-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 From: Isaku Yamahata Define an enum kvm_tdp_mmu_root_types to specify the KVM MMU root type [1] so that the iterator on the root page table can consistently filter the root page table type instead of only_valid. TDX KVM will operate on KVM page tables with specified types. Shared page table, private page table, or both. Introduce an enum instead of bool only_valid so that we can easily enhance page table types applicable to shared, private, or both in addition to valid or not. Replace only_valid=false with KVM_ANY_ROOTS and only_valid=true with KVM_ANY_VALID_ROOTS. Use KVM_ANY_ROOTS and KVM_ANY_VALID_ROOTS to wrap KVM_VALID_ROOTS to avoid further code churn when direct vs mirror root concepts are introduced in future patches. Link: https://lore.kernel.org/kvm/ZivazWQw1oCU8VBC@google.com/ [1] Suggested-by: Sean Christopherson Signed-off-by: Isaku Yamahata Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-11-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/tdp_mmu.c | 42 +++++++++++++++++++++----------------- arch/x86/kvm/mmu/tdp_mmu.h | 7 +++++++ 2 files changed, 30 insertions(+), 19 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index fbf835469390..965fa3b5a00b 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -92,9 +92,13 @@ void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root) call_rcu(&root->rcu_head, tdp_mmu_free_sp_rcu_callback); } -static bool tdp_mmu_root_match(struct kvm_mmu_page *root, bool only_valid) +static bool tdp_mmu_root_match(struct kvm_mmu_page *root, + enum kvm_tdp_mmu_root_types types) { - if (only_valid && root->role.invalid) + if (WARN_ON_ONCE(!(types & KVM_VALID_ROOTS))) + return false; + + if (root->role.invalid && !(types & KVM_INVALID_ROOTS)) return false; return true; @@ -102,17 +106,17 @@ static bool tdp_mmu_root_match(struct kvm_mmu_page *root, bool only_valid) /* * Returns the next root after @prev_root (or the first root if @prev_root is - * NULL). A reference to the returned root is acquired, and the reference to - * @prev_root is released (the caller obviously must hold a reference to - * @prev_root if it's non-NULL). + * NULL) that matches with @types. A reference to the returned root is + * acquired, and the reference to @prev_root is released (the caller obviously + * must hold a reference to @prev_root if it's non-NULL). * - * If @only_valid is true, invalid roots are skipped. + * Roots that doesn't match with @types are skipped. * * Returns NULL if the end of tdp_mmu_roots was reached. */ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, struct kvm_mmu_page *prev_root, - bool only_valid) + enum kvm_tdp_mmu_root_types types) { struct kvm_mmu_page *next_root; @@ -133,7 +137,7 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, typeof(*next_root), link); while (next_root) { - if (tdp_mmu_root_match(next_root, only_valid) && + if (tdp_mmu_root_match(next_root, types) && kvm_tdp_mmu_get_root(next_root)) break; @@ -158,20 +162,20 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, * If shared is set, this function is operating under the MMU lock in read * mode. */ -#define __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _only_valid) \ - for (_root = tdp_mmu_next_root(_kvm, NULL, _only_valid); \ +#define __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _types) \ + for (_root = tdp_mmu_next_root(_kvm, NULL, _types); \ ({ lockdep_assert_held(&(_kvm)->mmu_lock); }), _root; \ - _root = tdp_mmu_next_root(_kvm, _root, _only_valid)) \ + _root = tdp_mmu_next_root(_kvm, _root, _types)) \ if (_as_id >= 0 && kvm_mmu_page_as_id(_root) != _as_id) { \ } else #define for_each_valid_tdp_mmu_root_yield_safe(_kvm, _root, _as_id) \ - __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, true) + __for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, KVM_VALID_ROOTS) #define for_each_tdp_mmu_root_yield_safe(_kvm, _root) \ - for (_root = tdp_mmu_next_root(_kvm, NULL, false); \ + for (_root = tdp_mmu_next_root(_kvm, NULL, KVM_ALL_ROOTS); \ ({ lockdep_assert_held(&(_kvm)->mmu_lock); }), _root; \ - _root = tdp_mmu_next_root(_kvm, _root, false)) + _root = tdp_mmu_next_root(_kvm, _root, KVM_ALL_ROOTS)) /* * Iterate over all TDP MMU roots. Requires that mmu_lock be held for write, @@ -180,18 +184,18 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, * Holding mmu_lock for write obviates the need for RCU protection as the list * is guaranteed to be stable. */ -#define __for_each_tdp_mmu_root(_kvm, _root, _as_id, _only_valid) \ +#define __for_each_tdp_mmu_root(_kvm, _root, _as_id, _types) \ list_for_each_entry(_root, &_kvm->arch.tdp_mmu_roots, link) \ if (kvm_lockdep_assert_mmu_lock_held(_kvm, false) && \ ((_as_id >= 0 && kvm_mmu_page_as_id(_root) != _as_id) || \ - !tdp_mmu_root_match((_root), (_only_valid)))) { \ + !tdp_mmu_root_match((_root), (_types)))) { \ } else #define for_each_tdp_mmu_root(_kvm, _root, _as_id) \ - __for_each_tdp_mmu_root(_kvm, _root, _as_id, false) + __for_each_tdp_mmu_root(_kvm, _root, _as_id, KVM_ALL_ROOTS) #define for_each_valid_tdp_mmu_root(_kvm, _root, _as_id) \ - __for_each_tdp_mmu_root(_kvm, _root, _as_id, true) + __for_each_tdp_mmu_root(_kvm, _root, _as_id, KVM_VALID_ROOTS) static struct kvm_mmu_page *tdp_mmu_alloc_sp(struct kvm_vcpu *vcpu) { @@ -1159,7 +1163,7 @@ bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, { struct kvm_mmu_page *root; - __for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, false) + __for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, KVM_ALL_ROOTS) flush = tdp_mmu_zap_leafs(kvm, root, range->start, range->end, range->may_block, flush); diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index 51884fc6a512..a2028d036c0c 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -19,6 +19,13 @@ __must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root) void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root); +enum kvm_tdp_mmu_root_types { + KVM_INVALID_ROOTS = BIT(0), + + KVM_VALID_ROOTS = BIT(1), + KVM_ALL_ROOTS = KVM_VALID_ROOTS | KVM_INVALID_ROOTS, +}; + bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, gfn_t start, gfn_t end, bool flush); bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp); void kvm_tdp_mmu_zap_all(struct kvm *kvm); From patchwork Fri Dec 13 19:57:04 2024 Content-Type: text/plain; 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Fri, 13 Dec 2024 19:57:27 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id A54E01956086; Fri, 13 Dec 2024 19:57:26 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com Subject: [PATCH 11/18] KVM: x86/tdp_mmu: Take root in tdp_mmu_for_each_pte() Date: Fri, 13 Dec 2024 14:57:04 -0500 Message-ID: <20241213195711.316050-12-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 From: Isaku Yamahata Take the root as an argument of tdp_mmu_for_each_pte() instead of looking it up in the mmu. With no other purpose of passing the mmu, drop it. Future changes will want to change which root is used based on the context of the MMU operation. So change the callers to pass in the root currently used, mmu->root.hpa in a preparatory patch to make the later one smaller and easier to review. Signed-off-by: Isaku Yamahata Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-12-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/tdp_mmu.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 965fa3b5a00b..297d05e5a4cd 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -647,8 +647,8 @@ static inline void tdp_mmu_iter_set_spte(struct kvm *kvm, struct tdp_iter *iter, continue; \ else -#define tdp_mmu_for_each_pte(_iter, _kvm, _mmu, _start, _end) \ - for_each_tdp_pte(_iter, _kvm, root_to_sp(_mmu->root.hpa), _start, _end) +#define tdp_mmu_for_each_pte(_iter, _kvm, _root, _start, _end) \ + for_each_tdp_pte(_iter, _kvm, _root, _start, _end) static inline bool __must_check tdp_mmu_iter_need_resched(struct kvm *kvm, struct tdp_iter *iter) @@ -1078,8 +1078,8 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter, */ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { - struct kvm_mmu *mmu = vcpu->arch.mmu; struct kvm *kvm = vcpu->kvm; + struct kvm_mmu_page *root = root_to_sp(vcpu->arch.mmu->root.hpa); struct tdp_iter iter; struct kvm_mmu_page *sp; int ret = RET_PF_RETRY; @@ -1090,7 +1090,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) rcu_read_lock(); - tdp_mmu_for_each_pte(iter, kvm, mmu, fault->gfn, fault->gfn + 1) { + tdp_mmu_for_each_pte(iter, kvm, root, fault->gfn, fault->gfn + 1) { int r; if (fault->nx_huge_page_workaround_enabled) @@ -1739,14 +1739,14 @@ bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm, int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level) { + struct kvm_mmu_page *root = root_to_sp(vcpu->arch.mmu->root.hpa); struct tdp_iter iter; - struct kvm_mmu *mmu = vcpu->arch.mmu; gfn_t gfn = addr >> PAGE_SHIFT; int leaf = -1; *root_level = vcpu->arch.mmu->root_role.level; - tdp_mmu_for_each_pte(iter, vcpu->kvm, mmu, gfn, gfn + 1) { + tdp_mmu_for_each_pte(iter, vcpu->kvm, root, gfn, gfn + 1) { leaf = iter.level; sptes[leaf] = iter.old_spte; } @@ -1768,11 +1768,11 @@ int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gfn_t gfn, u64 *spte) { + struct kvm_mmu_page *root = root_to_sp(vcpu->arch.mmu->root.hpa); struct tdp_iter iter; - struct kvm_mmu *mmu = vcpu->arch.mmu; tdp_ptep_t sptep = NULL; - tdp_mmu_for_each_pte(iter, vcpu->kvm, mmu, gfn, gfn + 1) { + tdp_mmu_for_each_pte(iter, vcpu->kvm, root, gfn, gfn + 1) { *spte = iter.old_spte; sptep = iter.sptep; } From patchwork Fri Dec 13 19:57:05 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907835 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 99DBF1F5408 for ; 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Fri, 13 Dec 2024 14:57:30 -0500 X-MC-Unique: OYyeI7O7N76B_ohU0ICZxA-1 X-Mimecast-MFC-AGG-ID: OYyeI7O7N76B_ohU0ICZxA Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D9B1E195608A; Fri, 13 Dec 2024 19:57:28 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id CABB01956086; Fri, 13 Dec 2024 19:57:27 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com, Kai Huang Subject: [PATCH 12/18] KVM: x86/tdp_mmu: Support mirror root for TDP MMU Date: Fri, 13 Dec 2024 14:57:05 -0500 Message-ID: <20241213195711.316050-13-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 From: Isaku Yamahata Add the ability for the TDP MMU to maintain a mirror of a separate mapping. Like other Coco technologies, TDX has the concept of private and shared memory. For TDX the private and shared mappings are managed on separate EPT roots. The private half is managed indirectly through calls into a protected runtime environment called the TDX module, where the shared half is managed within KVM in normal page tables. In order to handle both shared and private memory, KVM needs to learn to handle faults and other operations on the correct root for the operation. KVM could learn the concept of private roots, and operate on them by calling out to operations that call into the TDX module. But there are two problems with that: 1. Calls into the TDX module are relatively slow compared to the simple accesses required to read a PTE managed directly by KVM. 2. Other Coco technologies deal with private memory completely differently and it will make the code confusing when being read from their perspective. Special operations added for TDX that set private or zap private memory will have nothing to do with these other private memory technologies. (SEV, etc). To handle these, instead teach the TDP MMU about a new concept "mirror roots". Such roots maintain page tables that are not actually mapped, and are just used to traverse quickly to determine if the mid level page tables need to be installed. When the memory be mirrored needs to actually be changed, calls can be made to via x86_ops. private KVM page fault | | | V | private GPA | CPU protected EPTP | | | V | V mirror PT root | external PT root | | | V | V mirror PT --hook to propagate-->external PT | | | \--------------------+------\ | | | | | V V | private guest page | | non-encrypted memory | encrypted memory | Leave calling out to actually update the private page tables that are being mirrored for later changes. Just implement the handling of MMU operations on to mirrored roots. In order to direct operations to correct root, add root types KVM_DIRECT_ROOTS and KVM_MIRROR_ROOTS. Tie the usage of mirrored/direct roots to private/shared with conditionals. It could also be implemented by making the kvm_tdp_mmu_root_types and kvm_gfn_range_filter enum bits line up such that conversion could be a direct assignment with a case. Don't do this because the mapping of private to mirrored is confusing enough. So it is worth not hiding the logic in type casting. Cleanup the mirror root in kvm_mmu_destroy() instead of the normal place in kvm_mmu_free_roots(), because the private root that is being cannot be rebuilt like a normal root. It needs to persist for the lifetime of the VM. The TDX module will also need to be provided with page tables to use for the actual mapping being mirrored by the mirrored page tables. Allocate these in the mapping path using the recently added kvm_mmu_alloc_external_spt(). Don't support 2M page for now. This is avoided by forcing 4k pages in the fault. Add a KVM_BUG_ON() to verify. Signed-off-by: Isaku Yamahata Co-developed-by: Kai Huang Signed-off-by: Kai Huang Co-developed-by: Yan Zhao Signed-off-by: Yan Zhao Co-developed-by: Rick Edgecombe Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-13-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu.h | 16 ++++++++++++ arch/x86/kvm/mmu/mmu.c | 12 ++++++++- arch/x86/kvm/mmu/tdp_mmu.c | 31 ++++++++++++++++++------ arch/x86/kvm/mmu/tdp_mmu.h | 43 ++++++++++++++++++++++++++++++--- 5 files changed, 91 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 95f2b0890a58..dc8e4460a4bc 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -458,6 +458,7 @@ struct kvm_mmu { int (*sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int i); struct kvm_mmu_root_info root; + hpa_t mirror_root_hpa; union kvm_cpu_role cpu_role; union kvm_mmu_page_role root_role; diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 091002975374..d1775a38ffd3 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -104,6 +104,15 @@ void kvm_mmu_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu) { + /* + * Checking root.hpa is sufficient even when KVM has mirror root. + * We can have either: + * (1) mirror_root_hpa = INVALID_PAGE, root.hpa = INVALID_PAGE + * (2) mirror_root_hpa = root, root.hpa = INVALID_PAGE + * (3) mirror_root_hpa = root1, root.hpa = root2 + * We don't ever have: + * mirror_root_hpa = INVALID_PAGE, root.hpa = root + */ if (likely(vcpu->arch.mmu->root.hpa != INVALID_PAGE)) return 0; @@ -297,4 +306,11 @@ static inline gfn_t kvm_gfn_direct_bits(const struct kvm *kvm) { return kvm->arch.gfn_direct_bits; } + +static inline bool kvm_is_addr_direct(struct kvm *kvm, gpa_t gpa) +{ + gpa_t gpa_direct_bits = gfn_to_gpa(kvm_gfn_direct_bits(kvm)); + + return !gpa_direct_bits || (gpa & gpa_direct_bits); +} #endif diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 9b6c28b30298..4594fbdd0dcc 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3676,7 +3676,10 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) int r; if (tdp_mmu_enabled) { - kvm_tdp_mmu_alloc_root(vcpu); + if (kvm_has_mirrored_tdp(vcpu->kvm) && + !VALID_PAGE(mmu->mirror_root_hpa)) + kvm_tdp_mmu_alloc_root(vcpu, true); + kvm_tdp_mmu_alloc_root(vcpu, false); return 0; } @@ -6293,6 +6296,7 @@ static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) mmu->root.hpa = INVALID_PAGE; mmu->root.pgd = 0; + mmu->mirror_root_hpa = INVALID_PAGE; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID; @@ -7241,6 +7245,12 @@ int kvm_mmu_vendor_module_init(void) void kvm_mmu_destroy(struct kvm_vcpu *vcpu) { kvm_mmu_unload(vcpu); + if (tdp_mmu_enabled) { + read_lock(&vcpu->kvm->mmu_lock); + mmu_free_root_page(vcpu->kvm, &vcpu->arch.mmu->mirror_root_hpa, + NULL); + read_unlock(&vcpu->kvm->mmu_lock); + } free_mmu_pages(&vcpu->arch.root_mmu); free_mmu_pages(&vcpu->arch.guest_mmu); mmu_free_memory_caches(vcpu); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 297d05e5a4cd..d17a3cf1596d 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -101,7 +101,9 @@ static bool tdp_mmu_root_match(struct kvm_mmu_page *root, if (root->role.invalid && !(types & KVM_INVALID_ROOTS)) return false; - return true; + if (likely(!is_mirror_sp(root))) + return types & KVM_DIRECT_ROOTS; + return types & KVM_MIRROR_ROOTS; } /* @@ -236,7 +238,7 @@ static void tdp_mmu_init_child_sp(struct kvm_mmu_page *child_sp, tdp_mmu_init_sp(child_sp, iter->sptep, iter->gfn, role); } -void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu) +void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu, bool mirror) { struct kvm_mmu *mmu = vcpu->arch.mmu; union kvm_mmu_page_role role = mmu->root_role; @@ -244,6 +246,9 @@ void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu) struct kvm *kvm = vcpu->kvm; struct kvm_mmu_page *root; + if (mirror) + role.is_mirror = true; + /* * Check for an existing root before acquiring the pages lock to avoid * unnecessary serialization if multiple vCPUs are loading a new root. @@ -295,8 +300,12 @@ void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu) * and actually consuming the root if it's invalidated after dropping * mmu_lock, and the root can't be freed as this vCPU holds a reference. */ - mmu->root.hpa = __pa(root->spt); - mmu->root.pgd = 0; + if (mirror) { + mmu->mirror_root_hpa = __pa(root->spt); + } else { + mmu->root.hpa = __pa(root->spt); + mmu->root.pgd = 0; + } } static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, @@ -1078,8 +1087,8 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter, */ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { + struct kvm_mmu_page *root = tdp_mmu_get_root_for_fault(vcpu, fault); struct kvm *kvm = vcpu->kvm; - struct kvm_mmu_page *root = root_to_sp(vcpu->arch.mmu->root.hpa); struct tdp_iter iter; struct kvm_mmu_page *sp; int ret = RET_PF_RETRY; @@ -1117,13 +1126,18 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) */ sp = tdp_mmu_alloc_sp(vcpu); tdp_mmu_init_child_sp(sp, &iter); + if (is_mirror_sp(sp)) + kvm_mmu_alloc_external_spt(vcpu, sp); sp->nx_huge_page_disallowed = fault->huge_page_disallowed; - if (is_shadow_present_pte(iter.old_spte)) + if (is_shadow_present_pte(iter.old_spte)) { + /* Don't support large page for mirrored roots (TDX) */ + KVM_BUG_ON(is_mirror_sptep(iter.sptep), vcpu->kvm); r = tdp_mmu_split_huge_page(kvm, &iter, sp, true); - else + } else { r = tdp_mmu_link_sp(kvm, &iter, sp, true); + } /* * Force the guest to retry if installing an upper level SPTE @@ -1768,7 +1782,8 @@ int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gfn_t gfn, u64 *spte) { - struct kvm_mmu_page *root = root_to_sp(vcpu->arch.mmu->root.hpa); + /* Fast pf is not supported for mirrored roots */ + struct kvm_mmu_page *root = tdp_mmu_get_root(vcpu, KVM_DIRECT_ROOTS); struct tdp_iter iter; tdp_ptep_t sptep = NULL; diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index a2028d036c0c..9887441cd703 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -10,7 +10,7 @@ void kvm_mmu_init_tdp_mmu(struct kvm *kvm); void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm); -void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu); +void kvm_tdp_mmu_alloc_root(struct kvm_vcpu *vcpu, bool private); __must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root) { @@ -21,11 +21,48 @@ void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root); enum kvm_tdp_mmu_root_types { KVM_INVALID_ROOTS = BIT(0), - - KVM_VALID_ROOTS = BIT(1), + KVM_DIRECT_ROOTS = BIT(1), + KVM_MIRROR_ROOTS = BIT(2), + KVM_VALID_ROOTS = KVM_DIRECT_ROOTS | KVM_MIRROR_ROOTS, KVM_ALL_ROOTS = KVM_VALID_ROOTS | KVM_INVALID_ROOTS, }; +static inline enum kvm_tdp_mmu_root_types kvm_gfn_range_filter_to_root_types(struct kvm *kvm, + enum kvm_gfn_range_filter process) +{ + enum kvm_tdp_mmu_root_types ret = 0; + + if (!kvm_has_mirrored_tdp(kvm)) + return KVM_DIRECT_ROOTS; + + if (process & KVM_FILTER_PRIVATE) + ret |= KVM_MIRROR_ROOTS; + if (process & KVM_FILTER_SHARED) + ret |= KVM_DIRECT_ROOTS; + + WARN_ON_ONCE(!ret); + + return ret; +} + +static inline struct kvm_mmu_page *tdp_mmu_get_root_for_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + if (unlikely(!kvm_is_addr_direct(vcpu->kvm, fault->addr))) + return root_to_sp(vcpu->arch.mmu->mirror_root_hpa); + + return root_to_sp(vcpu->arch.mmu->root.hpa); +} + +static inline struct kvm_mmu_page *tdp_mmu_get_root(struct kvm_vcpu *vcpu, + enum kvm_tdp_mmu_root_types type) +{ + if (unlikely(type == KVM_MIRROR_ROOTS)) + return root_to_sp(vcpu->arch.mmu->mirror_root_hpa); + + return root_to_sp(vcpu->arch.mmu->root.hpa); +} + bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, gfn_t start, gfn_t end, bool flush); bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp); void kvm_tdp_mmu_zap_all(struct kvm *kvm); From patchwork Fri Dec 13 19:57:06 2024 Content-Type: text/plain; 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Fri, 13 Dec 2024 19:57:30 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 180661956086; Fri, 13 Dec 2024 19:57:28 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com Subject: [PATCH 13/18] KVM: x86/tdp_mmu: Propagate attr_filter to MMU notifier callbacks Date: Fri, 13 Dec 2024 14:57:06 -0500 Message-ID: <20241213195711.316050-14-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Teach the MMU notifier callbacks how to check kvm_gfn_range.process to filter which KVM MMU root types to operate on. The private GPAs are backed by guest memfd. Such memory is not subjected to MMU notifier callbacks because it can't be mapped into the host user address space. Now kvm_gfn_range conveys info about which root to operate on. Enhance the callback to filter the root page table type. The KVM MMU notifier comes down to two functions. kvm_tdp_mmu_unmap_gfn_range() and __kvm_tdp_mmu_age_gfn_range(): - invalidate_range_start() calls kvm_tdp_mmu_unmap_gfn_range() - invalidate_range_end() doesn't call into arch code - the other callbacks call __kvm_tdp_mmu_age_gfn_range() For VM's without a private/shared split in the EPT, all operations should target the normal(direct) root. With the switch from for_each_tdp_mmu_root() to __for_each_tdp_mmu_root() in kvm_tdp_mmu_handle_gfn(), there are no longer any users of for_each_tdp_mmu_root(). Remove it. Signed-off-by: Isaku Yamahata Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-14-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/tdp_mmu.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index d17a3cf1596d..9a004c999a28 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -193,9 +193,6 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, !tdp_mmu_root_match((_root), (_types)))) { \ } else -#define for_each_tdp_mmu_root(_kvm, _root, _as_id) \ - __for_each_tdp_mmu_root(_kvm, _root, _as_id, KVM_ALL_ROOTS) - #define for_each_valid_tdp_mmu_root(_kvm, _root, _as_id) \ __for_each_tdp_mmu_root(_kvm, _root, _as_id, KVM_VALID_ROOTS) @@ -1172,12 +1169,16 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) return ret; } +/* Used by mmu notifier via kvm_unmap_gfn_range() */ bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, bool flush) { + enum kvm_tdp_mmu_root_types types; struct kvm_mmu_page *root; - __for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, KVM_ALL_ROOTS) + types = kvm_gfn_range_filter_to_root_types(kvm, range->attr_filter) | KVM_INVALID_ROOTS; + + __for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, types) flush = tdp_mmu_zap_leafs(kvm, root, range->start, range->end, range->may_block, flush); @@ -1217,17 +1218,21 @@ static bool __kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, bool test_only) { + enum kvm_tdp_mmu_root_types types; struct kvm_mmu_page *root; struct tdp_iter iter; bool ret = false; + types = kvm_gfn_range_filter_to_root_types(kvm, range->attr_filter); + /* * Don't support rescheduling, none of the MMU notifiers that funnel * into this helper allow blocking; it'd be dead, wasteful code. 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Like other Coco technologies, TDX has the concept of private and shared memory. For TDX the private and shared mappings are managed on separate EPT roots. The private half is managed indirectly through calls into a protected runtime environment called the TDX module, where the shared half is managed within KVM in normal page tables. Since calls into the TDX module are relatively slow, walking private page tables by making calls into the TDX module would not be efficient. Because of this, previous changes have taught the TDP MMU to keep a mirror root, which is separate, unmapped TDP root that private operations can be directed to. Currently this root is disconnected from any actual guest mapping. Now add plumbing to propagate changes to the "external" page tables being mirrored. Just create the x86_ops for now, leave plumbing the operations into the TDX module for future patches. Add two operations for setting up external page tables, one for linking new page tables and one for setting leaf PTEs. Don't add any op for configuring the root PFN, as TDX handles this itself. Don't provide a way to set permissions on the PTEs also, as TDX doesn't support it. This results in MMU "mirroring" support that is very targeted towards TDX. Since it is likely there will be no other user, the main benefit of making the support generic is to keep TDX specific *looking* code outside of the MMU. As a generic feature it will make enough sense from TDX's perspective. For developers unfamiliar with TDX arch it can express the general concepts such that they can continue to work in the code. TDX MMU support will exclude certain MMU operations, so only plug in the mirroring x86 ops where they will be needed. For setting/linking, only hook tdp_mmu_set_spte_atomic() which is used for mapping and linking PTs. Don't bother hooking tdp_mmu_iter_set_spte() as it is only used for setting PTEs in operations unsupported by TDX: splitting huge pages and write protecting. Sprinkle KVM_BUG_ON()s to document as code that these paths are not supported for mirrored page tables. For zapping operations, leave those for near future changes. Many operations in the TDP MMU depend on atomicity of the PTE update. While the mirror PTE on KVM's side can be updated atomically, the update that happens inside the external operations (S-EPT updates via TDX module call) can't happen atomically with the mirror update. The following race could result during two vCPU's populating private memory: * vcpu 1: atomically update 2M level mirror EPT entry to be present * vcpu 2: read 2M level EPT entry that is present * vcpu 2: walk down into 4K level EPT * vcpu 2: atomically update 4K level mirror EPT entry to be present * vcpu 2: set_exterma;_spte() to update 4K secure EPT entry => error because 2M secure EPT entry is not populated yet * vcpu 1: link_external_spt() to update 2M secure EPT entry Prevent this by setting the mirror PTE to FROZEN_SPTE while the reflect operations are performed. Only write the actual mirror PTE value once the reflect operations have completed. When trying to set a PTE to present and encountering a frozen SPTE, retry the fault. By doing this the race is prevented as follows: * vcpu 1: atomically update 2M level EPT entry to be FROZEN_SPTE * vcpu 2: read 2M level EPT entry that is FROZEN_SPTE * vcpu 2: find that the EPT entry is frozen abandon page table walk to resume guest execution * vcpu 1: link_external_spt() to update 2M secure EPT entry * vcpu 1: atomically update 2M level EPT entry to be present (unfreeze) * vcpu 2: resume guest execution Depending on vcpu 1 state, vcpu 2 may result in EPT violation again or make progress on guest execution Signed-off-by: Isaku Yamahata Co-developed-by: Kai Huang Signed-off-by: Kai Huang Co-developed-by: Yan Zhao Signed-off-by: Yan Zhao Co-developed-by: Rick Edgecombe Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-15-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm-x86-ops.h | 2 + arch/x86/include/asm/kvm_host.h | 7 +++ arch/x86/kvm/mmu/tdp_mmu.c | 94 ++++++++++++++++++++++++++---- 3 files changed, 92 insertions(+), 11 deletions(-) diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h index 5aff7222e40f..dbbdaa8586ab 100644 --- a/arch/x86/include/asm/kvm-x86-ops.h +++ b/arch/x86/include/asm/kvm-x86-ops.h @@ -94,6 +94,8 @@ KVM_X86_OP_OPTIONAL_RET0(set_tss_addr) KVM_X86_OP_OPTIONAL_RET0(set_identity_map_addr) KVM_X86_OP_OPTIONAL_RET0(get_mt_mask) KVM_X86_OP(load_mmu_pgd) +KVM_X86_OP_OPTIONAL(link_external_spt) +KVM_X86_OP_OPTIONAL(set_external_spte) KVM_X86_OP(has_wbinvd_exit) KVM_X86_OP(get_l2_tsc_offset) KVM_X86_OP(get_l2_tsc_multiplier) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index dc8e4460a4bc..b973fda8528a 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1758,6 +1758,13 @@ struct kvm_x86_ops { void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level); + /* Update external mapping with page table link. */ + int (*link_external_spt)(struct kvm *kvm, gfn_t gfn, enum pg_level level, + void *external_spt); + /* Update the external page table from spte getting set. */ + int (*set_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level, + kvm_pfn_t pfn_for_gfn); + bool (*has_wbinvd_exit)(void); u64 (*get_l2_tsc_offset)(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 9a004c999a28..7ba1f0ce99c8 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -440,6 +440,59 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared) call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); } +static void *get_external_spt(gfn_t gfn, u64 new_spte, int level) +{ + if (is_shadow_present_pte(new_spte) && !is_last_spte(new_spte, level)) { + struct kvm_mmu_page *sp = spte_to_child_sp(new_spte); + + WARN_ON_ONCE(sp->role.level + 1 != level); + WARN_ON_ONCE(sp->gfn != gfn); + return sp->external_spt; + } + + return NULL; +} + +static int __must_check set_external_spte_present(struct kvm *kvm, tdp_ptep_t sptep, + gfn_t gfn, u64 old_spte, + u64 new_spte, int level) +{ + bool was_present = is_shadow_present_pte(old_spte); + bool is_present = is_shadow_present_pte(new_spte); + bool is_leaf = is_present && is_last_spte(new_spte, level); + kvm_pfn_t new_pfn = spte_to_pfn(new_spte); + int ret = 0; + + KVM_BUG_ON(was_present, kvm); + + lockdep_assert_held(&kvm->mmu_lock); + /* + * We need to lock out other updates to the SPTE until the external + * page table has been modified. Use FROZEN_SPTE similar to + * the zapping case. + */ + if (!try_cmpxchg64(sptep, &old_spte, FROZEN_SPTE)) + return -EBUSY; + + /* + * Use different call to either set up middle level + * external page table, or leaf. + */ + if (is_leaf) { + ret = static_call(kvm_x86_set_external_spte)(kvm, gfn, level, new_pfn); + } else { + void *external_spt = get_external_spt(gfn, new_spte, level); + + KVM_BUG_ON(!external_spt, kvm); + ret = static_call(kvm_x86_link_external_spt)(kvm, gfn, level, external_spt); + } + if (ret) + __kvm_tdp_mmu_write_spte(sptep, old_spte); + else + __kvm_tdp_mmu_write_spte(sptep, new_spte); + return ret; +} + /** * handle_changed_spte - handle bookkeeping associated with an SPTE change * @kvm: kvm instance @@ -540,7 +593,8 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, handle_removed_pt(kvm, spte_to_child_pt(old_spte, level), shared); } -static inline int __must_check __tdp_mmu_set_spte_atomic(struct tdp_iter *iter, +static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm, + struct tdp_iter *iter, u64 new_spte) { u64 *sptep = rcu_dereference(iter->sptep); @@ -553,15 +607,25 @@ static inline int __must_check __tdp_mmu_set_spte_atomic(struct tdp_iter *iter, */ WARN_ON_ONCE(iter->yielded || is_frozen_spte(iter->old_spte)); - /* - * Note, fast_pf_fix_direct_spte() can also modify TDP MMU SPTEs and - * does not hold the mmu_lock. On failure, i.e. if a different logical - * CPU modified the SPTE, try_cmpxchg64() updates iter->old_spte with - * the current value, so the caller operates on fresh data, e.g. if it - * retries tdp_mmu_set_spte_atomic() - */ - if (!try_cmpxchg64(sptep, &iter->old_spte, new_spte)) - return -EBUSY; + if (is_mirror_sptep(iter->sptep) && !is_frozen_spte(new_spte)) { + int ret; + + ret = set_external_spte_present(kvm, iter->sptep, iter->gfn, + iter->old_spte, new_spte, iter->level); + if (ret) + return ret; + } else { + /* + * Note, fast_pf_fix_direct_spte() can also modify TDP MMU SPTEs + * and does not hold the mmu_lock. On failure, i.e. if a + * different logical CPU modified the SPTE, try_cmpxchg64() + * updates iter->old_spte with the current value, so the caller + * operates on fresh data, e.g. if it retries + * tdp_mmu_set_spte_atomic() + */ + if (!try_cmpxchg64(sptep, &iter->old_spte, new_spte)) + return -EBUSY; + } return 0; } @@ -591,7 +655,7 @@ static inline int __must_check tdp_mmu_set_spte_atomic(struct kvm *kvm, lockdep_assert_held_read(&kvm->mmu_lock); - ret = __tdp_mmu_set_spte_atomic(iter, new_spte); + ret = __tdp_mmu_set_spte_atomic(kvm, iter, new_spte); if (ret) return ret; @@ -631,6 +695,14 @@ static u64 tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep, old_spte = kvm_tdp_mmu_write_spte(sptep, old_spte, new_spte, level); handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level, false); + + /* + * Users that do non-atomic setting of PTEs don't operate on mirror + * roots, so don't handle it and bug the VM if it's seen. + */ + if (is_mirror_sptep(sptep)) + KVM_BUG_ON(is_shadow_present_pte(new_spte), kvm); + return old_spte; } From patchwork Fri Dec 13 19:57:08 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907833 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 261EF1F4E5B for ; Fri, 13 Dec 2024 19:57:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119858; cv=none; b=hwsaqk0/x/P1Pw/0R7OjpB8XH5WXAfqtsfzNCG2mUJaOxXMFR2QFqsGNCtE3nqCDqKh5FhuLv5mkNCqNkC1xG3lhuku9OHLv8lmj1dBb4nZI+LiQHv2PtFTj6OstjqaoJDCaUiLqCPzEveNdHhRyVr9cCWR5Ujuy6eiLBuXZXxU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119858; c=relaxed/simple; bh=x3YJeohR8Zu+SW+j4ksh1UBDoLuVt+QNwHZXX2B0F6I=; 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Fri, 13 Dec 2024 19:57:32 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 7E6631956089; Fri, 13 Dec 2024 19:57:31 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com, Kai Huang Subject: [PATCH 15/18] KVM: x86/tdp_mmu: Propagate tearing down mirror page tables Date: Fri, 13 Dec 2024 14:57:08 -0500 Message-ID: <20241213195711.316050-16-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 From: Isaku Yamahata Integrate hooks for mirroring page table operations for cases where TDX will zap PTEs or free page tables. Like other Coco technologies, TDX has the concept of private and shared memory. For TDX the private and shared mappings are managed on separate EPT roots. The private half is managed indirectly though calls into a protected runtime environment called the TDX module, where the shared half is managed within KVM in normal page tables. Since calls into the TDX module are relatively slow, walking private page tables by making calls into the TDX module would not be efficient. Because of this, previous changes have taught the TDP MMU to keep a mirror root, which is separate, unmapped TDP root that private operations can be directed to. Currently this root is disconnected from the guest. Now add plumbing to propagate changes to the "external" page tables being mirrored. Just create the x86_ops for now, leave plumbing the operations into the TDX module for future patches. Add two operations for tearing down page tables, one for freeing page tables (free_external_spt) and one for zapping PTEs (remove_external_spte). Define them such that remove_external_spte will perform a TLB flush as well. (in TDX terms "ensure there are no active translations"). TDX MMU support will exclude certain MMU operations, so only plug in the mirroring x86 ops where they will be needed. For zapping/freeing, only hook tdp_mmu_iter_set_spte() which is used for mapping and linking PTs. Don't bother hooking tdp_mmu_set_spte_atomic() as it is only used for zapping PTEs in operations unsupported by TDX: zapping collapsible PTEs and kvm_mmu_zap_all_fast(). In previous changes to address races around concurrent populating using tdp_mmu_set_spte_atomic(), a solution was introduced to temporarily set FROZEN_SPTE in the mirrored page tables while performing the external operations. Such a solution is not needed for the tear down paths in TDX as these will always be performed with the mmu_lock held for write. Sprinkle some KVM_BUG_ON()s to reflect this. Signed-off-by: Isaku Yamahata Co-developed-by: Kai Huang Signed-off-by: Kai Huang Co-developed-by: Yan Zhao Signed-off-by: Yan Zhao Co-developed-by: Rick Edgecombe Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-16-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm-x86-ops.h | 2 ++ arch/x86/include/asm/kvm_host.h | 8 +++++ arch/x86/kvm/mmu/tdp_mmu.c | 51 +++++++++++++++++++++++++++++- 3 files changed, 60 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h index dbbdaa8586ab..c82cd6635402 100644 --- a/arch/x86/include/asm/kvm-x86-ops.h +++ b/arch/x86/include/asm/kvm-x86-ops.h @@ -96,6 +96,8 @@ KVM_X86_OP_OPTIONAL_RET0(get_mt_mask) KVM_X86_OP(load_mmu_pgd) KVM_X86_OP_OPTIONAL(link_external_spt) KVM_X86_OP_OPTIONAL(set_external_spte) +KVM_X86_OP_OPTIONAL(free_external_spt) +KVM_X86_OP_OPTIONAL(remove_external_spte) KVM_X86_OP(has_wbinvd_exit) KVM_X86_OP(get_l2_tsc_offset) KVM_X86_OP(get_l2_tsc_multiplier) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b973fda8528a..5c220cda4672 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1765,6 +1765,14 @@ struct kvm_x86_ops { int (*set_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level, kvm_pfn_t pfn_for_gfn); + /* Update external page tables for page table about to be freed. */ + int (*free_external_spt)(struct kvm *kvm, gfn_t gfn, enum pg_level level, + void *external_spt); + + /* Update external page table from spte getting removed, and flush TLB. */ + int (*remove_external_spte)(struct kvm *kvm, gfn_t gfn, enum pg_level level, + kvm_pfn_t pfn_for_gfn); + bool (*has_wbinvd_exit)(void); u64 (*get_l2_tsc_offset)(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 7ba1f0ce99c8..140902a7b291 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -340,6 +340,29 @@ static void tdp_mmu_unlink_sp(struct kvm *kvm, struct kvm_mmu_page *sp) spin_unlock(&kvm->arch.tdp_mmu_pages_lock); } +static void remove_external_spte(struct kvm *kvm, gfn_t gfn, u64 old_spte, + int level) +{ + kvm_pfn_t old_pfn = spte_to_pfn(old_spte); + int ret; + + /* + * External (TDX) SPTEs are limited to PG_LEVEL_4K, and external + * PTs are removed in a special order, involving free_external_spt(). + * But remove_external_spte() will be called on non-leaf PTEs via + * __tdp_mmu_zap_root(), so avoid the error the former would return + * in this case. + */ + if (!is_last_spte(old_spte, level)) + return; + + /* Zapping leaf spte is allowed only when write lock is held. */ + lockdep_assert_held_write(&kvm->mmu_lock); + /* Because write lock is held, operation should success. */ + ret = static_call(kvm_x86_remove_external_spte)(kvm, gfn, level, old_pfn); + KVM_BUG_ON(ret, kvm); +} + /** * handle_removed_pt() - handle a page table removed from the TDP structure * @@ -435,6 +458,23 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared) } handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, old_spte, FROZEN_SPTE, level, shared); + + if (is_mirror_sp(sp)) { + KVM_BUG_ON(shared, kvm); + remove_external_spte(kvm, gfn, old_spte, level); + } + } + + if (is_mirror_sp(sp) && + WARN_ON(static_call(kvm_x86_free_external_spt)(kvm, base_gfn, sp->role.level, + sp->external_spt))) { + /* + * Failed to free page table page in mirror page table and + * there is nothing to do further. + * Intentionally leak the page to prevent the kernel from + * accessing the encrypted page. + */ + sp->external_spt = NULL; } call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); @@ -610,6 +650,13 @@ static inline int __must_check __tdp_mmu_set_spte_atomic(struct kvm *kvm, if (is_mirror_sptep(iter->sptep) && !is_frozen_spte(new_spte)) { int ret; + /* + * Users of atomic zapping don't operate on mirror roots, + * so don't handle it and bug the VM if it's seen. + */ + if (KVM_BUG_ON(!is_shadow_present_pte(new_spte), kvm)) + return -EBUSY; + ret = set_external_spte_present(kvm, iter->sptep, iter->gfn, iter->old_spte, new_spte, iter->level); if (ret) @@ -700,8 +747,10 @@ static u64 tdp_mmu_set_spte(struct kvm *kvm, int as_id, tdp_ptep_t sptep, * Users that do non-atomic setting of PTEs don't operate on mirror * roots, so don't handle it and bug the VM if it's seen. */ - if (is_mirror_sptep(sptep)) + if (is_mirror_sptep(sptep)) { KVM_BUG_ON(is_shadow_present_pte(new_spte), kvm); + remove_external_spte(kvm, gfn, old_spte, level); + } return old_spte; } From patchwork Fri Dec 13 19:57:09 2024 Content-Type: text/plain; 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Fri, 13 Dec 2024 19:57:33 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id C0C141956086; Fri, 13 Dec 2024 19:57:32 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com, Chao Gao Subject: [PATCH 16/18] KVM: x86/tdp_mmu: Take root types for kvm_tdp_mmu_invalidate_all_roots() Date: Fri, 13 Dec 2024 14:57:09 -0500 Message-ID: <20241213195711.316050-17-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 From: Isaku Yamahata Rename kvm_tdp_mmu_invalidate_all_roots() to kvm_tdp_mmu_invalidate_roots(), and make it enum kvm_tdp_mmu_root_types as an argument. kvm_tdp_mmu_invalidate_roots() is called with different root types. For kvm_mmu_zap_all_fast() it only operates on shared roots. But when tearing down a VM it needs to invalidate all roots. Have the callers only invalidate the required roots instead of all roots. Within kvm_tdp_mmu_invalidate_roots(), respect the root type passed by checking the root type in root iterator. Suggested-by: Chao Gao Signed-off-by: Isaku Yamahata Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-17-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 9 +++++++-- arch/x86/kvm/mmu/tdp_mmu.c | 15 +++++++++++++-- arch/x86/kvm/mmu/tdp_mmu.h | 3 ++- 3 files changed, 22 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 4594fbdd0dcc..c948d344b3fb 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6466,8 +6466,13 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) * write and in the same critical section as making the reload request, * e.g. before kvm_zap_obsolete_pages() could drop mmu_lock and yield. */ - if (tdp_mmu_enabled) - kvm_tdp_mmu_invalidate_all_roots(kvm); + if (tdp_mmu_enabled) { + /* + * External page tables don't support fast zapping, therefore + * their mirrors must be invalidated separately by the caller. + */ + kvm_tdp_mmu_invalidate_roots(kvm, KVM_DIRECT_ROOTS); + } /* * Notify all vcpus to reload its shadow page table and flush TLB. diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 140902a7b291..94c464ce1d12 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -37,7 +37,7 @@ void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) * for zapping and thus puts the TDP MMU's reference to each root, i.e. * ultimately frees all roots. */ - kvm_tdp_mmu_invalidate_all_roots(kvm); + kvm_tdp_mmu_invalidate_roots(kvm, KVM_VALID_ROOTS); kvm_tdp_mmu_zap_invalidated_roots(kvm, false); WARN_ON(atomic64_read(&kvm->arch.tdp_mmu_pages)); @@ -1070,10 +1070,18 @@ void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm, bool shared) * Note, kvm_tdp_mmu_zap_invalidated_roots() is gifted the TDP MMU's reference. * See kvm_tdp_mmu_alloc_root(). */ -void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm) +void kvm_tdp_mmu_invalidate_roots(struct kvm *kvm, + enum kvm_tdp_mmu_root_types root_types) { struct kvm_mmu_page *root; + /* + * Invalidating invalid roots doesn't make sense, prevent developers from + * having to think about it. + */ + if (WARN_ON_ONCE(root_types & KVM_INVALID_ROOTS)) + root_types &= ~KVM_INVALID_ROOTS; + /* * mmu_lock must be held for write to ensure that a root doesn't become * invalid while there are active readers (invalidating a root while @@ -1095,6 +1103,9 @@ void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm) * or get/put references to roots. */ list_for_each_entry(root, &kvm->arch.tdp_mmu_roots, link) { + if (!tdp_mmu_root_match(root, root_types)) + continue; + /* * Note, invalid roots can outlive a memslot update! Invalid * roots must be *zapped* before the memslot update completes, diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index 9887441cd703..52acf99d40a0 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -66,7 +66,8 @@ static inline struct kvm_mmu_page *tdp_mmu_get_root(struct kvm_vcpu *vcpu, bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, gfn_t start, gfn_t end, bool flush); bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp); void kvm_tdp_mmu_zap_all(struct kvm *kvm); -void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm); +void kvm_tdp_mmu_invalidate_roots(struct kvm *kvm, + enum kvm_tdp_mmu_root_types root_types); void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm, bool shared); int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault); From patchwork Fri Dec 13 19:57:10 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907839 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1351E1F7070 for ; 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Fri, 13 Dec 2024 14:57:36 -0500 X-MC-Unique: gKG02AP1MMitMI3ysszi7w-1 X-Mimecast-MFC-AGG-ID: gKG02AP1MMitMI3ysszi7w Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1C7CB19560A2; Fri, 13 Dec 2024 19:57:35 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 29D891956086; Fri, 13 Dec 2024 19:57:34 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com Subject: [PATCH 17/18] KVM: x86/tdp_mmu: Don't zap valid mirror roots in kvm_tdp_mmu_zap_all() Date: Fri, 13 Dec 2024 14:57:10 -0500 Message-ID: <20241213195711.316050-18-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 From: Rick Edgecombe Don't zap valid mirror roots in kvm_tdp_mmu_zap_all(), which in effect is only direct roots (invalid and valid). For TDX, kvm_tdp_mmu_zap_all() is only called during MMU notifier release. Since, mirrored EPT comes from guest mem, it will never be mapped to userspace, and won't apply. But in addition to be unnecessary, mirrored EPT is cleaned up in a special way during VM destruction. Pass the KVM_INVALID_ROOTS bit into __for_each_tdp_mmu_root_yield_safe() as well, to clean up invalid direct roots, as is the current behavior. Co-developed-by: Yan Zhao Signed-off-by: Yan Zhao Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-18-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/tdp_mmu.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 94c464ce1d12..e08c60834d0c 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -999,19 +999,23 @@ void kvm_tdp_mmu_zap_all(struct kvm *kvm) struct kvm_mmu_page *root; /* - * Zap all roots, including invalid roots, as all SPTEs must be dropped - * before returning to the caller. Zap directly even if the root is - * also being zapped by a worker. Walking zapped top-level SPTEs isn't - * all that expensive and mmu_lock is already held, which means the - * worker has yielded, i.e. flushing the work instead of zapping here - * isn't guaranteed to be any faster. + * Zap all roots, except valid mirror roots, as all direct SPTEs must + * be dropped before returning to the caller. For TDX, mirror roots + * don't need handling in response to the mmu notifier (the caller) and + * they also won't be invalid until the VM is being torn down. + * + * Zap directly even if the root is also being zapped by a worker. + * Walking zapped top-level SPTEs isn't all that expensive and mmu_lock + * is already held, which means the worker has yielded, i.e. flushing + * the work instead of zapping here isn't guaranteed to be any faster. * * A TLB flush is unnecessary, KVM zaps everything if and only the VM * is being destroyed or the userspace VMM has exited. In both cases, * KVM_RUN is unreachable, i.e. no vCPUs will ever service the request. */ lockdep_assert_held_write(&kvm->mmu_lock); - for_each_tdp_mmu_root_yield_safe(kvm, root) + __for_each_tdp_mmu_root_yield_safe(kvm, root, -1, + KVM_DIRECT_ROOTS | KVM_INVALID_ROOTS) tdp_mmu_zap_root(kvm, root, false); } From patchwork Fri Dec 13 19:57:11 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13907838 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7C43B1F7066 for ; Fri, 13 Dec 2024 19:57:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119862; cv=none; b=nFTm0UBh9UZAfMQmLGollW0BdXBIVsdLT3/deIkQxTyjeNkRY5KBtCeLrSk49up8vJM6ny46W9wDhYpdcv+p0wBmxfoQL87fdzBQP4GRWJRrnosUCXcbSSOdfrOAKfzS8bd43u9mXzm1dVJdzdA67QcsQO6POCHj5k2kq42etp0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734119862; c=relaxed/simple; bh=7FV91zj3iAwh7l0LvpU4SVIBXF4+EOaMZMQhC9b3k9o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=P32lcksIe7U/HdOaXt7RxSbf5PKZLGXiiCstluag87uzLvyxzaMo8jq5ImPQuZb5lWkmP+zO2jQ1ODoeHMEdOlFmpFBsCyWj90nQhKhale+ukrY40MbTYYiek5q1Qy2SehVs0J9EkYfEx8T4c4uavfPczmzzqmuFcenxi7NU0Ag= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=h8/Vv+jn; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="h8/Vv+jn" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734119859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6AdfFYYPbrCfemeQilBocin4u1dKdrIY8L1F+QT3Jro=; b=h8/Vv+jnhaDQlGstOIAtQmkEfZfk1GRpVR2xoUfJ5mMBrP/MsKqhZuEGTIMbfg/FXFNBrN pYCOhy5KkiJebCTtGjUSWxZo/c6Ed+J1bLhKAMxEyjpEDwwi8WwK3LQhx+QpwAM5kWdvMy 0uh9tHZvKGUOeYiPVvLu+BzieTxGI3M= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-164-DDzxqgmpNhm7NAXI6mVRIw-1; Fri, 13 Dec 2024 14:57:38 -0500 X-MC-Unique: DDzxqgmpNhm7NAXI6mVRIw-1 X-Mimecast-MFC-AGG-ID: DDzxqgmpNhm7NAXI6mVRIw Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5EA1619560A3; Fri, 13 Dec 2024 19:57:36 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 4EFB81956086; Fri, 13 Dec 2024 19:57:35 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: yan.y.zhao@intel.com, isaku.yamahata@intel.com, binbin.wu@linux.intel.com, rick.p.edgecombe@intel.com, Sean Christopherson Subject: [PATCH 18/18] KVM: x86/mmu: Prevent aliased memslot GFNs Date: Fri, 13 Dec 2024 14:57:11 -0500 Message-ID: <20241213195711.316050-19-pbonzini@redhat.com> In-Reply-To: <20241213195711.316050-1-pbonzini@redhat.com> References: <20241213195711.316050-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 From: Rick Edgecombe Add a few sanity checks to prevent memslot GFNs from ever having alias bits set. Like other Coco technologies, TDX has the concept of private and shared memory. For TDX the private and shared mappings are managed on separate EPT roots. The private half is managed indirectly though calls into a protected runtime environment called the TDX module, where the shared half is managed within KVM in normal page tables. For TDX, the shared half will be mapped in the higher alias, with a "shared bit" set in the GPA. However, KVM will still manage it with the same memslots as the private half. This means memslot looks ups and zapping operations will be provided with a GFN without the shared bit set. If these memslot GFNs ever had the bit that selects between the two aliases it could lead to unexpected behavior in the complicated code that directs faulting or zapping operations between the roots that map the two aliases. As a safety measure, prevent memslots from being set at a GFN range that contains the alias bit. Also, check in the kvm_faultin_pfn() for the fault path. This later check does less today, as the alias bits are specifically stripped from the GFN being checked, however future code could possibly call in to the fault handler in a way that skips this stripping. Since kvm_faultin_pfn() now has many references to vcpu->kvm, extract it to local variable. Link: https://lore.kernel.org/kvm/ZpbKqG_ZhCWxl-Fc@google.com/ Suggested-by: Sean Christopherson Signed-off-by: Rick Edgecombe Message-ID: <20240718211230.1492011-19-rick.p.edgecombe@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu.h | 5 +++++ arch/x86/kvm/mmu/mmu.c | 10 +++++++--- arch/x86/kvm/x86.c | 3 +++ 3 files changed, 15 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index d1775a38ffd3..878061d0063e 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -313,4 +313,9 @@ static inline bool kvm_is_addr_direct(struct kvm *kvm, gpa_t gpa) return !gpa_direct_bits || (gpa & gpa_direct_bits); } + +static inline bool kvm_is_gfn_alias(struct kvm *kvm, gfn_t gfn) +{ + return gfn & kvm_gfn_direct_bits(kvm); +} #endif diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index c948d344b3fb..81feccee3866 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4403,8 +4403,12 @@ static int kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, unsigned int access) { struct kvm_memory_slot *slot = fault->slot; + struct kvm *kvm = vcpu->kvm; int ret; + if (KVM_BUG_ON(kvm_is_gfn_alias(kvm, fault->gfn), kvm)) + return -EFAULT; + /* * Note that the mmu_invalidate_seq also serves to detect a concurrent * change in attributes. is_page_fault_stale() will detect an @@ -4418,7 +4422,7 @@ static int kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, * Now that we have a snapshot of mmu_invalidate_seq we can check for a * private vs. shared mismatch. */ - if (fault->is_private != kvm_mem_is_private(vcpu->kvm, fault->gfn)) { + if (fault->is_private != kvm_mem_is_private(kvm, fault->gfn)) { kvm_mmu_prepare_memory_fault_exit(vcpu, fault); return -EFAULT; } @@ -4480,7 +4484,7 @@ static int kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, * *guaranteed* to need to retry, i.e. waiting until mmu_lock is held * to detect retry guarantees the worst case latency for the vCPU. */ - if (mmu_invalidate_retry_gfn_unsafe(vcpu->kvm, fault->mmu_seq, fault->gfn)) + if (mmu_invalidate_retry_gfn_unsafe(kvm, fault->mmu_seq, fault->gfn)) return RET_PF_RETRY; ret = __kvm_mmu_faultin_pfn(vcpu, fault); @@ -4500,7 +4504,7 @@ static int kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, * overall cost of failing to detect the invalidation until after * mmu_lock is acquired. */ - if (mmu_invalidate_retry_gfn_unsafe(vcpu->kvm, fault->mmu_seq, fault->gfn)) { + if (mmu_invalidate_retry_gfn_unsafe(kvm, fault->mmu_seq, fault->gfn)) { kvm_mmu_finish_page_fault(vcpu, fault, RET_PF_RETRY); return RET_PF_RETRY; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index daf59233bef4..d81242288cf8 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -13010,6 +13010,9 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, if ((new->base_gfn + new->npages - 1) > kvm_mmu_max_gfn()) return -EINVAL; + if (kvm_is_gfn_alias(kvm, new->base_gfn + new->npages - 1)) + return -EINVAL; + return kvm_alloc_memslot_metadata(kvm, new); }